Crystal Field Engineering of Pr-Activated Gehlenite with Near Golden Ultraviolet C Emission for 100% Sterilization Efficiency

Abstract

Ultraviolet C (UVC) sterilization has the advantages of high efficiency, broad spectrum, and no secondary pollution. However, the emission wavelength of UVC phosphors still suffers from a large deviation from the golden sterilization wavelength of 265 nm and a low luminescence intensity. Herein, we report UVC emission near the golden sterilization wavelength as well as a long afterglow through crystal field engineering, which can lead to 100% sterilization efficiency. Combined with theoretical calculation and experimental studies, substitution of Ca 2+ with large-sized Sr 2+ could obtain slight expansion and distortion of cationic sites, resulting in a decrease in crystal field intensity and blue shift of Ca 1.5 Sr 0.5 Al 2 SiO 7 :1%Pr 3+ , and produce near golden UVC emission. Ca 1.5 Sr 0.5 Al 2 SiO 7 :1%Pr 3+ phosphor can effectively inactivate Staphylococcus aureus within 10 min, showing more efficiency than the traditional mercury lamp. This work provides an effective solution for the design and preparation of UVC phosphors using crystal field engineering toward near golden UVC emission.

Stimulated-source-independent persistent luminescence phosphor Sr2Ta2O7:Tb3+, Tm3+ for multi-mode anti-counterfeiting applications

“…When the coordination number (CN) is six, the ionic radii of Sr 2+ (CN = 6, r = 1.18 Å) is closer to that of Tb 3+ (CN = 6, r = 0.92 Å) and Tm 3+ (CN = 6, r = 0.88 Å) than Ta 5+ (CN = 6, r = 0.64 Å), and the relative radius differences between Tb 3+ /Tm 3+ and Sr 2+ (CN = 6, Δ R = 22.03/25.42%) are smaller than those of Tb 3+ /Tm 3+ and Ta 3+ (CN = 6, Δ R = 43.75/37.50%) (Table S1, ESI†), which indicates that Tb 3+ and Tm 3+ prefer to enter into Sr1O 6 sites rather than TaO 6 octahedra. 26,27 However, it is difficult to distinguish the selective occupancy tendency between Sr1O 6 and Sr2O 12 because of the lack of ionic radii in Tb 3+ and Tm 3+ with a CN of twelve. Therefore, the formation energy ( E form ) of different Tb-/Tm-substituted sites was calculated.…”

Double Gain of Efficient UV‐C Phosphor and Fast Scintillator Based on Pr3+‐doped KY3F10 Nano‐Glass Composites

“…[ 8 ] More importantly, the energy position of the lowest 5 d level of Pr 3+ is sensitive to crystal‐field (CF) strength such that a strong CF with a large splitting pushes its position down below 1 S 0 , which is the prerequisite for the observation of 5 d → 4 f transitions at the UV‐C region. [ 9 ] Previously, efficient cathodoluminescence (CL) UV‐C emissions were mostly found in Pr 3+ ‐doped wide‐band gap crystals such as CaSiO 3 (emitting at 276 nm), [ 10 ] Ca 2 Al 2 SiO 7 (268 nm), [ 7b ] Ca 1.5 Sr 0.5 Al 2 SiO 7 (270 nm), [ 11 ] Sr 3 (BO 3 ) 2 (272 nm), [ 7a ] YPO 4 (233 nm) etc., [ 12 ] but seldom in silica [ 13 ] and phosphate glasses. [ 14 ] Sharma et al.…”